The present invention relates to dedusting and dust removal of gas generally, specifically under utilization of a dust pre-precipitator or preliminary deduster and filters arranged downstream and operated in a dry method or mode, there being a dust bag or the like connected to a discharge part of the pre-precipitator for collecting some of the dust that has been removed from gas to be cleaned.
Arrangements of the type to which the invention pertains, use a flushing gas blower by means of which each filter container can be individually connected to a separate circuit for purposes of cleaning the filter elements and, under utilization of a relatively high flushing gas pressure as compared with the normal operating pressure. Also pure or clean gas is usually extractable at the discharge opening of the filter arranged in the upper part thereof.
Dedusting and dust removal equipment generally to which the invention pertains, are classified usually in a manner which considers the combination of filters and pre-precipitator operating as a unit, the filters themselves operate in parallel. In such a case it is possible, at least in principle, to take one of the filters temporarily out of the filter arrangement and to clean it in a counterflow method, while the remaining filters continue the dedusting operation. The cleaning requirement makes in fact a parallel operation of several filters mandatory, unless dedusting is to be interrupted in its entirety. In addition to the principle of parallel opertion it is necessary to move the dust from the filters in some fashion out of the system using preferably a short transport or moving past. Particularly, if dust is removed from the filters in a horizontal fashion, it was found that they easily cake together or form lumps.
German printed patent application 29 27 317 corresponding to U.S. Pat No. 4,244,715 suggests to connect several filter containers at their respective inputs directly to the pre-precipitator using separate raw gas tubes for the connection. Also, the exit or discharge end of the various filter containers are manifolded and connected to a common pure or clean gas collection line. Appropriate connect and disconnect valves are provided at the inlet and discharge outlets of each of the filter containers. Moreover separate dust discharge tubes are provided leading to the filter containers the pre-precipitator. Hence, this known equipment solves the problem of providing a space saving association between filter containers and dust pre-precipitators, using relatively simple sealing techniques vis-a-vis the outer atmosphere, while at the same time improving maintenance of the filter containers. Specifically here a space saving arrangement is attained by arranging the various filter containers around the dust pre-precipitator, which in fact avoids the need for double sealing at the outlet or discharge of the filters.
However, it was found that the distribution of the prededusted gas to the individual filters and filter containers still can stand some improvement as far as regular operation is concerned and to be maintained particularly when one or the other filter is temporarily operationally removed for purposes of cleaning. Moreover, it was found that the number of connect and disconnect valves, that are subject to considerable wear should be lowered.